Mattress



FIG. 1 is a perspective view of a mattress in accordance with the present design;

FIG. 2 is a top view thereof, the top and bottom views being identical;

FIG. 3 is a front view thereof, the front and rear views being identical;

FIG. 4 is side view thereof, both side views being identical;

FIG. 5 is a perspective view of another mattress in accordance with the present design;

FIG. 6 is a top view thereof, the top and bottom views being identical;

FIG. 7 is a front view thereof, the front and rear views being identical; and,

FIG. 8 is side view thereof, both side views being identical. 

CLAIM The ornamental design for a mattress, as shown and described. 